One of radiographic inspection apparatuses is a computed tomography (CT) apparatus. The CT apparatus comprises an X-ray tube for radiating X-ray fan beams, and a radiation detector comprising a large number of radiation detection elements. The X-ray tube and the radiation detector are arranged oppositely to each other with an object to be measured at a center. X-ray fan beams radiated from the X-ray tube pass through the object to be measured, and are detected by the radiation detector. With every radiation having a changed angle, X-ray absorption data are collected to calculate X-ray absorbance at each position in each cross section of the object by computer analysis, thereby forming an image based on the X-ray absorbance. The radiation detector may be a detector comprising a combination of a scintillator array and silicon photodiodes, or a detector comprising a scintillator array and photomultiplier tubes.
JP 2001-174564 A discloses an X-ray detector array comprising two types of scintillator elements arranged in an X-ray-transmitting direction for detecting X-rays with different energy distributions, and light-detecting elements each corresponding to each scintillator element arranged in a direction perpendicular to the scintillator elements, pluralities of scintillator elements and pluralities of light-detecting elements being aligned in line. Pluralities of scintillator elements are integrally molded by a light-reflecting material in a two-dimensional matrix pattern. JP 2001-174564 A illustrates an example in which three-stage scintillator elements are arranged in an X-ray-transmitting direction a direction). However, JP 2001-174564 A fails to specifically disclose the production method of the X-ray detector array.
As a dual energy detector comprising two types of scintillators with different sensitivity distributions of X-ray energy detection, WO 2006/114715 (JP 2008-538966 A) discloses a radiation detector comprising upper scintillators arranged opposite to an X-ray source for receiving radiations and converting low-energy radiations to light while permitting high-energy radiations to transmit, first light detectors each receiving the light from each upper scintillator for converting it to electric signals, lower scintillators for converting the transmitted high-energy radiations to light, and second light detectors each receiving the light from each lower scintillator for converting it to electric signals. However, WO 2006/114715 fails to specifically disclose the production method of a scintillator array.
JP 9-211139 A discloses a radiation detector comprising scintillators capable of emitting light by receiving radiations, and light detectors each converting the light from each scintillator to electric signals, the scintillators being a combination of ceramic scintillators and single-crystal scintillators. The ceramic scintillators are polycrystalline Gd2O2S:Pr, etc., and the single-crystal scintillators are CdWO4, Bi6Ge4O12, etc. In Examples, after the ceramic scintillators and the single-crystal scintillators are bonded with an epoxy adhesive, photodiodes are bonded to the single-crystal scintillator, and a light-reflecting TiO2 layer is formed on the top surfaces of the ceramic scintillators. However, the production method of such scintillator suffers large numbers of steps.